First-principles study of strain stabilization of Ge(105) facet on Si(001)

Lu, Guang Hong; C̆uma, Martin; Liu, Feng

doi:10.1103/physrevb.72.125415

Cited by 97 publications

(85 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering that both ͕001͖ and ͕105͖ facets are found close to the island top, where strain relaxation is strong, values of around 64-66 meV/ Å 2 can be expected for these facets. 18 For the ͕113͖ surface, an estimate of about 62 meV/ Å 2 was found by DFT for unstrained Ge͑113͒. 48 However, the ͕15 3 23͖ surface was never analyzed by DFT because of the very large unit cell.…”

Section: Appendix: Model Parametersmentioning

confidence: 99%

“…5͑c͒ were obtained using ␥ pyr = 59.8 meV/ Å 2 . This value was deduced from DFT calculations, 18 leading to ͑biaxial͒ straindependent values which we averaged over the pyramid facet after determining the position-dependent strain field by FEM. While this procedure appears to be solid 49 some error ͑DFT is not exact and the strain at the pyramid facet is not fully biaxial͒ must be expected.…”

Section: Appendix: Model Parametersmentioning

confidence: 99%

“…Indeed, it has been shown that the energetics of the WL is strongly thickness dependent up to a Ge coverage ͑⌰ Ge ͒ of 4-5 ML. [16][17][18] Thus, in this range of ⌰ Ge the appearance of stable islands is expected to critically depend on both, the volume as well as on the WL thickness.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Key role of the wetting layer in revealing the hidden path of Ge/Si(001) Stranski-Krastanow growth onset

et al. 2009

View full text Add to dashboard Cite

The commonly accepted Stranski-Krastanow model, according to which island formation occurs on top of a wetting layer ͑WL͒ of a certain thickness, predicts for the morphological evolution an increasing island aspect ratio with volume. We report on an apparent violation of this thermodynamic understanding of island growth with deposition. In order to investigate the actual onset of three-dimensional islanding and the critical WL thickness in the Ge/Si͑001͒ system, a key issue is controlling the Ge deposition with extremely high resolution ͓0.025 monolayer ͑ML͔͒. Atomic force microscopy and photoluminescence measurements on samples covering the deposition range 1.75-6.1 ML, taken along a Ge deposition gradient on 4 in. Si substrates and at different growth temperatures ͑T g ͒, surprisingly reveal that for T g Ͼ 675°C steeper multifaceted domes apparently nucleate prior to shallow ͕105͖-faceted pyramids, in a narrow commonly overlooked deposition range. The puzzling experimental findings are explained by a quantitative modeling of the total energy with deposition. We accurately matched ab initio calculations of layer and surface energies to finite-element method simulations of the elastic energy in islands, in order to compare the thermodynamic stability of different island shapes with respect to an increasing WL thickness. Close agreement between modeling and experiments is found, pointing out that the sizeable progressive lowering of the surface energy in the first few MLs of the WL reverts the common understanding of the SK growth onset. Strong similarities between islanding in SiGe and III/V systems are highlighted.

show abstract

Section: Appendix: Model Parametersmentioning

confidence: 99%

Section: Appendix: Model Parametersmentioning

confidence: 99%

See 1 more Smart Citation

Key role of the wetting layer in revealing the hidden path of Ge/Si(001) Stranski-Krastanow growth onset

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Such facets typically include those expected from the ECS of the unstressed material (see discussion in Section 2.2) but strain effects might affect their relative extensions [198] and eventually induce the formation of additional facets (e.g. the common {105} facets observed on Ge islands [12], whose presence in the crystal shape is possible only because of a strong stabilization effect due to strain [43][44][45]). …”

Section: Faceting and Shape-transitionsmentioning

confidence: 99%

“…The most striking example is given by Ge{105} whose surface energy is stabilized by compression [43][44][45] to the point that the (001) wetting layer can spontaneously break into {105} faceting [7,46]. Micron-long, horizontal Ge wires delimited by {105} facets, have been recently observed [24,47] and shown to display peculiar electronic properties.…”

Section: Introductionmentioning

confidence: 99%

Continuum modelling of semiconductor heteroepitaxy: an applied perspective

Bergamaschini

Salvalaglio

Backofen

et al. 2016

Advances in Physics: X

View full text Add to dashboard Cite

Semiconductor heteroepitaxy involves a wealth of qualitatively different, competing phenomena. Examples include threedimensional island formation, injection of dislocations, mixing between film and substrate atoms. Their relative importance depends on the specific growth conditions, giving rise to a very complex scenario. The need for an optimal control over heteroepitaxial films and/or nanostructures is widespread: semiconductor epitaxy by molecular beam epitaxy or chemical vapour deposition is nowadays exploited also in industrial environments. Simulation models can be precious in limiting the parameter space to be sampled while aiming at films/nanostructures with the desired properties. In order to be appealing (and useful) to an applied audience, such models must yield predictions directly comparable with experimental data. This implies matching typical time scales and sizes, while offering a satisfactory description of the main physical driving forces. It is the aim of the present review to show that continuum models of semiconductor heteroepitaxy evolved significantly, providing a promising tool (even a working tool, in some cases) to comply with the above requirements. Several examples, spanning from the nanometre to the micron scale, are illustrated. Current limitations and future research directions are also discussed.

show abstract